This invention relates to a composite motor which controls the rotation of two motors with a single inverter.
Tokkai-Hei-8-340663 published by the Japanese Patent Office in 1996 discloses a motor/generator disposing a single stator and two rotors co-axially.
In this motor/generator, the stator is provided with two groups of coils which are independent on each other Each group of coils generates a rotating magnetic field for each rotor. Under this rotating magnetic field, the rotor rotates in synchronism with the rotating magnetic field. The two rotors are therefore driven independently according to the power currents supplied to these groups of coils.
In order to supply power currents of different wave forms, the motor/generator has two independent inverters. Accordingly, the construction of the motor/generator is complicated and the switching loss in the inverters is also large.
It is therefore an object of this invention to reduce current loss of a motor/generator provided with two rotors.
It is a further object of this Invention to facilitate current control of a motor/generator provided with two rotors.
It is a still further object of this invention to simplify the construction of a motor/generator provided with two rotors.
In order to achieve the above objects, this invention provides a motor/generator comprising a first rotor, a second rotor, a stator, an inverter and a microprocessor.
The first rotor comprises a plurality of protruding poles made of a magnetic material not magnetized. The second rotor comprises a plurality of poles. The stator comprises a plurality of coils and faces the first rotor and the second rotor. The inverter supplies an alternating current to the coils in response to a signal from the microprocessor.
The microprocessor is programmed calculate a first alternating current with which the coils generate a rotating magnetic field rotating in synchronism with the first rotor, calculate a second alternating current with which the coils generate a rotating magnetic field rotating in synchronism with the second rotor, calculate a composite current comprising the first alternating current and the second alternating current; and output the signal corresponding to the composite current to the inverter.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.